I can't find a DIY for flushing the radiator. Can someone tell me if this is the right procedure?

1. Let the engine cool down.
2. Put the car in ramps/jacks. * Make sure the car height is balanced. The Radiator reservoir has to be the highest.
3. Remove one of the Under body cover
4. Remove the radiator bleeder screw (underneath the car) and let it radiator bleed.
5. Reinstall the bleed screw
6. Fill the radiator with only water. Let the radiator cap off (Pressurized cap) and turn the engine and car heater on. *Keep an eye in the fluid level!!
7. Let the car run for 5-10 min then repeat steps 4-6 like 2 times.
8. After bleeding water, Install a new bleader screw and fill the radiator with 50% Antifreeze-50% water.
9. Turn the engine and car heater on and let the coolant flow with the radiator cap off (to release the air in the system)
10. Turn the engine off, check level and install the radiator cap.

If above steps are ok, I will do it today/tomorrow and post some pictures..

I'll be doing it this week. Have not researched it yet. Typically, I find block drain(s) and open those and also the radiator drain. Apparently the system holds 12 quarts so buy 3 gallons if using a pre-mix or 2 gallons if you are mixing with distilled water.

I'll be doing it this week. Have not researched it yet. Typically, I find block drain(s) and open those and also the radiator drain. Apparently the system holds 12 quarts so buy 3 gallons if using a pre-mix or 2 gallons if you are mixing with distilled water.

Make sure to use distilled water. It is okay to not know the capacity. Just keep mixing up your own 50/50 blend a little at a time and only add that mix. Keep in mind that there will be residual fluid left in the block after you do these water flushes unless BMW has a plug on the side of the block to remove to get that out. Toyota gives you a block plug to remove. So if you cannot do that, err on the strong side when blend up your coolant and water to end up at 50/50. If you truly knew the capacity, that would help. I would fill and drain 3x with distilled water if I was doing it.

So where is the block drain on the S65? No one has answered that question yet.

I have flushed coolant on E34, E36, and E39 so I understand the normal process. We are trying to figure out in this thread if there are any E9x M3 specific issues. I still have not gotten to this project so I have nothing to contribute yet.

So where is the block drain on the S65? No one has answered that question yet.

I have flushed coolant on E34, E36, and E39 so I understand the normal process. We are trying to figure out in this thread if there are any E9x M3 specific issues. I still have not gotten to this project so I have nothing to contribute yet.

I haven't crawled under there myself yet but if you've done those, then I'm sure you'll be fine. Same goes to anyone that's ever done a full coolant flush on a BMW.

There's nothing else down there. You're either draining oil or coolant from the block

Make sure to use distilled water. It is okay to not know the capacity. Just keep mixing up your own 50/50 blend a little at a time and only add that mix. Keep in mind that there will be residual fluid left in the block after you do these water flushes unless BMW has a plug on the side of the block to remove to get that out. Toyota gives you a block plug to remove. So if you cannot do that, err on the strong side when blend up your coolant and water to end up at 50/50. If you truly knew the capacity, that would help. I would fill and drain 3x with distilled water if I was doing it.

+1 on the distilled water,it's a cheap way to help prevent corrosion.tap water has a lot of minerals which are bad for radiators.i just had a radiator flush and refill done at the dealer,brought in 2 gallons of distilled water for them to use,1 was still about half full,so about 3 gallons was the total fill.

the manual says the coolant is lifetime fill.i plan to change it every 3-4 years.does anyone who is more mechanically savvy than me think it can really be left unchanged for the life of the car?

+1 on the distilled water,it's a cheap way to help prevent corrosion.tap water has a lot of minerals which are bad for radiators.i just had a radiator flush and refill done at the dealer,brought in 2 gallons of distilled water for them to use,1 was still about half full,so about 3 gallons was the total fill.

the manual says the coolant is lifetime fill.i plan to change it every 3-4 years.does anyone who is more mechanically savvy than me think it can really be left unchanged for the life of the car?

Wow it says it's a lifetime fluid? No way in hell. It starts breaking down after many heat cycles.

I don't track my car, but I still do a full fluid flush every 2 years. Easy job (although messy), but well worth it I think.

When they say "lifetime" they mean "it'll last long enough to make it until something else fails catastrophically to the point of needing a rebuild". For those who want 200k+ out of an engine, I'd change it more frequently than "never", or at least drain the rad and refill to get some of the more corrosive, higher dielectric stuff out and dilute it with fresh

1. Jack up the car and level. Remove the felt panels underneath the bumper (Left, Center and Right). They are mounted with 8mm screws and 3x 10mm screws on the back of the center piece connected to the metal skid plate.

(L piece - part# 51757896419, R piece - part# - 51757896420 )

- Unhooked (twist and slide to bigger hole) the hangers holding the center piece on both sides - part# 51757899820

2. Found the radiator drain plug (left side underneath the radiator).

3. Used a large phillips to unscrew it and drain.

4. Replugged the radiator drain hole with the old plug.

5. Filled the reservoir to about halfway with %50 BMW coolant / %50 distilled H20 (made separately in a container). The ball on the floating stick sat above the fill line.

6. Removed the bleed screw and fill cap. Start the engine and turn heater on highest temp without putting the fan on high.

7. I let the engine get to about 140 degrees F (took about 7-8 mins and heat starts coming out of cabin vents) and then shut down. Repeated steps 3.-6. three times using a new drain plug when done.

8. On the final fill, I filled to full and closed the bleed screw, opening and closing to let the air bubbles out while the engine is on. When there are no more bubbles, I used a turkey baster to remove some coolant from the reservoir.

The issues:

Since I did not know the volume of the coolant system, I did not try to flush the entire system using pure distilled water. The ratio of coolant to water would've been unknown when it came time to fill. I made a premix of 50/50 coolant/H20 and filled with that after each drain. Each drain yielded about 1 gallon of coolant.

What my method hopes to accomplish is to dilute old coolant with new coolant. This is why I mentioned this is NOT a flush but a way to get keep the coolant somewhat fresh. My car is just under 2 years old and I have about 28,000 miles.

If anyone knows a full flush method please let us know. For the time being, if anyone sees other problems with my method in addition to what I mentioned or has a better method than mine please let me and the rest of us know.

in some correspondence about radiator flushes with mike miller of roundel,he said that bmw had made it hard to do a full coolant flush on bmw's built after 2006 without extensive,and therefore expensive,disassembly,and that because of that the best you can do is drain and fill the radiator,which it looks like you have done.